1. Field of the Invention
The field of this invention relates to tailor-made amide-imide copolymers and terpolymers prepared from tricarboxylic acid anhydride derivatives, N,N'-diacylated diamines, N-acylated diamines and diamines and to molding resins and molded articles prepared therefrom.
2. Background
Amide-imide polymers and copolymers are a relatively new class of organic compounds known for their solubility in nitrogen-containing solvents when in the polyamic acid form. The major application of these amide-imides has been as wire enamels. This is illustrated in U.S. Pat. Nos. 3,817,942 (1974), 3,661,832 (1972), 3,494,890 (1970) and 3,347,828 (1967). British Specification No. 570,858 (1945) discloses the general state of the art. Amide-imide polymers and copolymers have also been found useful for molding application as shown in U.S. Pat. Nos. 4,016,140 (1977) and 3,573,260 (1971). Both are incorporated herein by reference. None of the foregoing references discloses tailor-made amide-imide copolymers and terpolymers.
The general object of this invention is to provide injection moldable linear high molecular weight amide-imide copolymers and terpolymers. A more specific object of this invention is to provide a novel process for preparing injection moldable tailored linear high molecular weight amide-imide copolymers and terpolymers by reacting acylated diamines with tricarboxylic acid anhydrides and diamines, at a temperature of about 50.degree. to 700.degree. F., wherein the imide, imide-imide, amide, amide-amide moieties incorporated into the polymer backbone can be controlled by acylating the amine functionality which is to form the amide and amide-amide moieties which polycondensation reaction is conducted at a temperature of about 300.degree. to about 700.degree. F. while reacting directly at a temperature of about 50.degree. F. to about 400.degree. F. those diamines with the tricarboxylic anhydride compound which are intended to form the imide and imide-imide moieties of the amide-imide copolymers and terpolymers. The molar ratio of the aromatic to aliphatic, cycloaliphatic and araliphatic diamines are suitably in the range of about 9:1 to 1:1, advantageously in the range of about 3:1 to 3:2.
In the novel process, the imide and imide-imide moieties incorporated into the polymer backbone are controlled by reacting at a temperature of about 50.degree. to about 400.degree. F. diamines with the tricarboxylic anhydride compound to form imide and imide-imide linkages and by the reaction of acylated diamines at a temperature of about 300.degree. to about 700.degree. F. to form amide and amide-amide linkages and sometimes acylated diamines at a temperature of about 350.degree. F. to about 700.degree. F. which form imide or imide-imide linkages. Generally the reaction of free amine groups is conducted prior to the reaction of acylated amine groups. Thus the initial temperature of the polymerization process is at the lower end of the ranges cited, from about 50.degree. F. to about 400.degree. F., and the final polymerization temperatures are in the range of about 300.degree. F. to about 700.degree. F. Generally, depending on the type of product desired, the range of acylation can be from about 40% of the total amine functionality up to 100% of the total amine functionality, preferably about 50-95% of the total amine functionality. Advantageously these monomers are mixed in the presence of solvents such as N-methylpyrrolidone, N,N-dimethylacetamide, acetic acid, etc. According to the process of this invention the copolymers and terpolymers may contain from two up to six different structural units set forth hereinbelow: ##STR1##
In the foregoing structural units Z is a trivalent aromatic radical. Z may be a trivalent radical of benzene, naphthalene, biphenyl, diphenyl ether, diphenyl sulfide, diphenyl sulfone, ditolyl ether, and the like.
Useful aromatic tricarboxylic acid anhydrides which contribute the trivalent radical moiety of Z include those compounds containing at least one pair of carboxyl groups in the ortho position with respect to each other or otherwise situated in a fashion which permits the formation of an anhydride structure, one other carboxyl group and from 9 to 21 carbon atoms. Within these limits, these compounds may contain one or more benzenoid rings such as, for instance, trimellitic anhydride and its isomers and multiring compounds such as the 1,8-anhydride of 1,3,8-tricarboxylnaphthalene. Usually these compounds contain up to three benzenoid rings. The preferred aromatic tricarboxylic acid anhydride employed in the novel process is trimellitic anhydride.
R.sub.1 is a divalent aromatic radical of six to twenty carbon atoms joined directly or containing stable linkages consisting of --S--, --O--, ##STR2## --SO.sub.2 --, --CO--, or methylene radicals. Aromatic diamines include para- and metaphenylenediamine, para- and meta-xylenediamine, paratoluenediamine, 2,4-toluenediamine, 2,6-toluenediamine, 3,5-toluenediamine, oxybis(aniline), thiobis(aniline), sulfonylbis(aniline), diaminobenzophenone, methylenebis(aniline), benzidine, 1,5-diaminonaphthalene, oxybis(2-methylaniline), thiobis(2-methylaniline), and the like. Examples of other useful aromatic primary diamines are the following: 2,2'-naphthalene diamine, 4,4'-naphthalene diamine, 2,2'-biphenylene diamine, 3,3'-biphenylene diamine, 4,4'-biphenylene diamine, and the like; 3,3'-dichlorobenzidine, ethylene dianiline (4,4'-diaminodiphenyl ethane), propylene dianiline (4,4'-diaminodiphenyl propane), and the like; ketodianiline, 3,3'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, hexafluoroisopropylidenebis(4-phenyl amine), 4,4'-diamino-diphenyl methane, 2,6-diaminopyridine, bis(4-aminophenyl)diethyl silane, bis(4-aminophenyl)ethyl phosphine oxide, bis(4-aminophenyl)phenyl phosphine oxide, bis(4-aminophenyl)-N-phenylamine, bis(4-aminophenyl)-N-methylamine, 3,3'-dimethyl-4,4'-diaminobiphenyl, para-bis(2-methyl-4-amino-phenyl)benzene, 3,3'-diaminoadamantane.
R.sub.2 is a divalent aliphatic, cycloaliphatic or araliphatic radical of from two to eighteen carbon atoms derived from aliphatic diamines such as ethylenediamine, propylenediamine, 2,2-dimethylpropylene diamine, tetramethylenediamine, hexamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, dodecamethylenediamine, 4,4'-diaminodicyclohexylmethane, meta- and paraxylylene diamine, 4,4'-diaminodicyclohexylethane, bis(aminocyclohexyl)propane, bis(para-aminocyclohexyl)sulfide, bis(aminocyclohexyl)sulfone, bis(aminocyclohexyl)ether, bis(aminocyclohexyl)diethyl silane, bis(aminocyclohexyl)ethyl phosphine oxide, bis(aminocyclohexyl)-phenyl phosphine oxide, bis(aminocyclohexyl)N-phenyl amine, bis(aminocyclohexyl)-N-methyl amine, 1,2-bis(3-aminopropoxy)ethane, 3-methoxyhexamethylenediamine, 2,5-dimethylheptamethylenediamine, 5-methylnonamethylenediamine, 1,4-diaminocyclohexane, 1,2-diaminooctadecane.
The diamines can suitably be acylated with aliphatic acids or anhydrides such as acetic anhydride, acetic acid, proprionic anhydride, etc., or any aliphatic acid or anhydride containing from 2 to 8 carbon atoms per acid, preferably 2 to 4 carbon atoms per acid or 4 to 16 carbon atoms per anhydride, preferably 4 to 8 carbon atoms. Formic acid or anhydride cannot be used to acylate the diamines.
Utilizing the novel process, seven different classes of amide-imide copolymers and terpolymers have been prepared. Suitably each copolymer and terpolymer is prepared utilizing both aromatic and aliphatic diamines. Usually the molar ratio of the aromatic to aliphatic diamines is in the range of 9:1 to 1:1. Advantageously, this range has been found to be 3:1 to 3:2. The copolymers and terpolymers have structural units as shown in Table I hereinbelow.
TABLE I ______________________________________ POLYMER CLASS STRUCTURAL UNITS ______________________________________ I A, B II A, C III A, B, C, D IV A, B, E V A, C, E VI A, B, C, D, E VII A, B, C, D, E, F ______________________________________
In the polymers of Classes I, II, and III the tricarboxylic acid anhydride group in the polymer is ordered head to head and tail to tail due to the order of the acylation of the diamines. Specifically, the ratio of diacylated diamine, trimellitic anhydride, unacylated diamine is maintained at about 1:2:1. The polymer of Class I is suitably prepared by diacylating the aliphatic, cycloaliphatic or araliphatic diamine and part of the aromatic diamine. The remainder of the aromatic diamine is reacted with two equivalents of the tricarboxylic acid anhydride compound to produce a bis imide/bis acid intermediate. The reaction between the bis imide/bis acid and the diacetyl derivative of the aromatic diamine produces Structural Unit A. In a similar manner the reaction between the bis imide/bis acid and the diacetyl derivative of the aliphatic, cycloaliphatic or araliphatic diamine produces Structural Unit B. The random dispersion of Structural Units A and B along the copolymer and terpolymer backbone thus make up the complete structure of Polymer I. When the polymer is further polymerized under solid state polymerization conditions at a temperature of about 400.degree. to 700.degree. F. a high molecular weight injection moldable copolymer and terpolymer is obtained having inherent viscosity in the range of 0.3 to 2.0. For the purpose of this invention inherent viscosity is measured at 25.degree. C. and 0.5% w/v in 60/40 w/w phenol/1,1,2,2-tetrachloroethane, N-methylpyrollidone or 100% sulfuric acid. The term "solid state polymerization" refers to chain extension of polymer molecules under conditions where the polymer molecules retain their solid form and do not become a fluid mass.
The copolymers and terpolymers of Class II are similar to polymers of Class I, but in this instance the aliphatic, cycloaliphatic and araliphatic diamine moieties are used directly to form imide groups (Structural Unit C) and the aromatic diamines are used to form either two amide groups by reaction of the diacylated derivative (Structural Unit A) or two imide groups by direct reaction of the diamine (Structural Unit C). The resultant Class II copolymers and terpolymers are made up of a random dispersion of units A and C. Class III copolymers and terpolymers are made up of Structural Units A, B, C and D and have all the trimellitoyl groups ordered head to head and tail to tail and all diamines are allowed either to form only two amide groups or two imide groups.
In copolymers and terpolymers of Class IV, V, and VI the aliphatic, cycloaliphatic and araliphatic diamines are used to form only di imide or di amide groups (Structural Units B, C, and D). Thus the trimellitoyl groups which are attached to the aliphatic or araliphatic diamines are ordered head to head or tail to tail. The aromatic diamines are acylated randomly, thus, some are diacylated while others are monoacylated or unacylated. The trimellitoyl groups which are attached to two aromatic diamine groups are randomly distributed between a head to head, a tail to tail, or a head to tail sequence (Structural Unit E). Polymer of Class IV is prepared by the reaction of diacylated alphatic, cycloaliphatic, or araliphaic diamines (which confines these amines to formation of two amide groups) with the tricarboxylic acid anhydride and un- or partially acylated aromatic diamines where the acylation level used is the amount that would give 50% acylation of all amine functionality utilized in the polymerization. By way of specific example, if a 3:1 ratio of aromatic to aliphatic diamine were used, all the aliphatic diamine would be diacylated and one third of the aromatic diamine functionality would be acylated. Polymer of Class V is prepared by the reaction of unacylated aliphatic, cycloaliphatic, or araliphatic diamines (which confines these amines to formation of two imide groups) with the tricarboxylic acid anhydride and fully or partially acylated aromatic diamines. The level of acylation can vary from 50% of the total amine functionality utilized in the reaction up to the aromatic diamine being fully diacylated. Polymer of Class VI is similar to the polymers of Class IV or V except that in polymers of Class VI the aliphatic diamines are used in both di imide or di amide formation and only about 50% of the total amine functionality is acylated. Polymers of Class VII are fully random in that both aliphatic diamine and aromatic diamine moieties are distributed between imide and amide portions and all trimellitoyl groups are free to be arranged head to head, tail to tail, or head to tail and 50 to 100% acylation of amine functionality is utilized. All of the foregoing polymers have an inherent viscosity in the range of 0.3 to 2.0 dl/g giving them molecular weights in the range of about 3,000 to 100,000. All these polymers can be injection molded and can be used as engineering plastics. They have excellent mechanical properties as shown in Table IV hereof.
With the use of Table II, a general method of preparation of these different polymers is herewith given. Polymers of Structural Classes I, II, III, V, and VII are prepared by first mixing and reacting the ingredients of columns J, K, and L usually in the presence of a solvent. If the acylating agent is active (e.g., an acid anhydride), reaction will occur readily at room temperature. When slow to react acylating agents (e.g., acetic acid) are used, this mixture must generally be heated to effect the proper amount of condensation. The reactants from columns P, Q, and R can be premixed, prereacted, or added separately to the prereacted mixture of J, K, and L. The solvent is removed by distillation and the mixture is polymerized under melt polycondensation conditions to yield the tailored polymer. Polymers of Structural Classes IV and VI are prepared by first mixing and reacting the ingredients of columns K and L, usually in the presence of a solvent. If the acylating agent is active (e.g., an acid anhydride), reaction will occur readily at room temperature. This is then followed by the addition of the ingredient from column P. After this mixture has reacted, the ingredients from columns Q and R can be added separately or in a premixed or prereacted form. When slow to react acylating agents are used (e.g., acetic acid), the mixture of K and L must generally be heated to effect the proper amount of condensation. After the addition of the ingredient from column P, a further period of heating will be required to effect the proper amount of condensation. After this mixture has reacted, the ingredients from columns Q and R can be added separately or in a premixed or prereacted form. The solvent is removed by distillation and the mixture is polymerized under melt polycondensation conditions to yield the tailored polymer. In certain cases the sequences of addition of reactants can be altered, but only to the extent that the level and type of acylation of the specific amine functionalities remain unchanged. In many cases, the melt prepared polymers from all structural classes are solid state polymerized prior to fabrication. However, further melt polymerization at 500.degree.-700.degree. F. may also be advantageously used in lieu of solid state polymerization to form the copolymer or terpolymer which is suitable for injection molding.
TABLE II __________________________________________________________________________ J K L P Q R MOLES MOLES MOLES OF MOLES MOLES MOLES STRUCTURAL OF OF ACYLATING OF OF OF CLASS ArDA RDA AGENT ArDA RDA TMA __________________________________________________________________________ ##STR3## T X ##STR4## O X II ##STR5## O X ##STR6## T X III ##STR7## M X ##STR8## T - M X IV O T X Y O X V Y O X to 2Y O T X VI O M X Y T - M X VII Y T X to 2X O O X __________________________________________________________________________
Acylating agents include acetic anhydride, acid or propionic acid or anhydride, etc., or any aliphatic acid or anhydride containing from 2 to 8 carbon atoms per acid, preferably 2 to 4 carbon atoms per acid or 4 to 16 carbon atoms per anhydride, preferably 4 to 8 carbon atoms. Formic acid cannot be used as an acylating agent in this process.
______________________________________ X = total moles TMA TMA = Trimellitic Anhydride Y = total moles ArDA ArDA = Aromatic Diamine T = total moles RDA RDA = Aliphatic Diamine X = Y + T O &lt; M &lt; T &lt; Y ______________________________________
By way of particular example, if it is desired to produce an amide-imide copolymer and terpolymer of Structural Class V wherein the ratio of aromatic to aliphatic diamines is 3 to 1 then X=4, Y=3 and T=1, and 3 moles of the aromatic diamine are acylated with 4 to 6 moles of the acylating agent. The acylating agent may be acetic acid, acetic anhydride or propionic anhydride or any aliphatic acid which contains from 2 to 8 carbon atoms or anhydride which contains from 4 to 16 carbon atoms. 4 moles of trimellitic compound are mixed or reacted with 1 mole of aliphatic diamine, or added separately to the acylated diamine mixture. The mixing is conducted in the presence of solvents such as N-methylpyrrolidone, N,N-dimethylacetamide, acetic acid, etc. The organic polar solvent is removed by distillation and the mixture is polymerized under melt polymerization conditions to yield an injection moldable copolymer and terpolymer of Class V. The novel process enables one to tailor the polymerization so that different structural classes can be incorporated depending on the properties desired in the resulting product. By way of specific examples, if long term thermal stability is of prime importance, one may wish to incorporate the aliphatic, cycloaliphatic or araliphatic into formation of the more stable imide group as shown in Structural Classes II and V. If impact is of prime importance, the polymers with a more random structure (Classes IV, V, VI, and especially VII) tend to have better impact properties. These copolymers and terpolymers have an inherent viscosity of 0.3 to 2.0 and heat deflection temperatures greater than 300.degree. F. without the use of fillers or fiber reinforcements. Although the first-stage melt polymerization products have an inherent viscosity of at least 0.2 dl/gram and can be used for injection molding application, it is generally preferable to start with a copolymer having been solid state polymerized or further melt polymerized.
The solid state polymerization which can be carried out below the melting point of the polymer can be conducted in several ways. However, all of the techniques require heating the ground or pelletized copolymers and terpolymers below the polymer melting point, generally at a temperature of about 400.degree. 550.degree. F., while either sparging with an inert gas, such as nitrogen or air, or operating under vacuum.
According to the novel process of this invention linear, high molecular weight copolymers and terpolymers have been prepared containing both aromatic and aliphatic moieties by a melt process. This in itself is a novel process feature since the prior art teaches only interfacial and solution polymerization techniques for the production of fully ordered head to head, tail to tail and completely random amide-imide polymers. Furthermore, according to the novel process a method for tailor-making amide-imide copolymers and terpolymers has been disclosed. These copolymers and terpolymers have excellent mechanical and thermal properties and can be readily injection molded. This injection moldability of these polymers can be partially contributed to the fact that these polymers are linear and are not cross-linked. Injection molding of the copolymers and terpolymers is accomplished by injecting the polymer into the mold maintained at a temperature of about 150.degree.-450.degree. F. In this process a 0.1-2.0 minute cycle is used with a barrel temperature of about 425.degree. F. to 650.degree. F. The injection molding conditions are given in Table III.
TABLE III ______________________________________ Mold Temperature 150-450.degree. F. Injection Pressure 1000-40,000 psi and held for 0.5-20.0 seconds Back Pressure 0-500 psi Cycle Time 6-120 seconds Extruder: Nozzle Temperature 425.degree. F. to 650.degree. F. Barrel Zones 425.degree. F. to 650.degree. F. Screw: 10-200 revolutions/minute ______________________________________
The mechanical properties of the copolymers and terpolymers prepared in Examples 1-10 are given in Table IV. Examples 11-14 teach the preparation of the 3:2:1 trimellitic anhydride:m-toluenediamine:1,6-hexanediamine polymers. The mechanical properties are given in Table V and show how the increase in randomness in going from Class V to Class VII increases impact. Table VI, however, shows how the direction of the aliphatic diamine to only imide formation in Class V can give better thermal stability. TBL3 TABLE IV MECHANICAL PROPERTIES OF COPOLYMERS AND TERPOLYMERS ASTM Polymer Class Method V IV VII V IV IV VII V V ArDA/RDA MBA/HMDA MBA/HMDA MBA/HMDA MBA/MXDA MBA/MXDA MPDA/HMDA MPDA/HMDA OBA/MXDA OBA/MXDA ArDA/RDA ratio 3/1 3/1 3/1 3/1 3/1 3/1 3/1 3/2 2/1 Tensile Strength, psi D-638 17,100 13,100 18,500 19,500 9,500 15,900 13,700 18,100 21,640 Tensile Modulus, D-638 psi 360,000 361,000 363,000 408,000 405,000 437,000 450,000 472,000 488,000 Elongation at D-638 Break, % 8.2 5.5 16.9 17.1 2.9 5.3 4.1 11.7 17.1 Flexural Strength, D-790 psi 24,400 22,200 23,500 26,600 14,100 26,700 26,700 28,400 30,200 Flexural Modulus, D-790 psi 501,000 451,000 460,000 527,000 508,000 584,000 573,000 586,000 614,000 Izod Impact, ft. D-256 lb./in. notch 0.46 0.38 1.99 0.38 0.36 0.36 0.33 0.42 0.63 Tensile Impact, D-1822 ft. lb./in..sup.2 56.2 32.1 72.3 120 6.5 50.7 48.0 56.9 38.3 H.D.T. @ 264 psi, D-648 .degree.F. 401 398 412 420 415 433 432 413 424 Density 1.29 1.29 1.29 1.30 1.30 1.35 1.35 1.33 1.34 Inherent viscosity 1.01 0.99 0.91 0.81 0.62 0.92 -- 1.26 1.41 Example # 1 5 9 6 7 4 10 2 8 ArDA = Aromatic diamine RDA = Aliphatic diamine MBA = Methylenebisaniline HMDA = 1,6Hexanediamine MXDA = Metaxylylenediamine OBA = Oxybisaniline MPDA = Metaphenylenediamine
The following Examples illustrate the preferred embodiments of this invention. It will be understood that these Examples are for illustration purposes only and do not purport to be wholly definitive with respect to the conditions or scope of this invention.